10/11/2009

No need to fast before cholesterol test, major analysis shows

Patients do not need to fast before doctors measure their cholesterol levels, a major new analysis funded by the British Heart Foundation (BHF) confirmed today.

After analysing data on over 300,000 people, researchers at the University of Cambridge concluded that tests can be made simpler and more convenient without making predictions less accurate.

Together, heart disease and stroke are the leading cause of death worldwide. Doctors currently use a combination of tests in a cardiovascular risk assessment to assess a patient’s likelihood of having a heart attack or stroke in the future. This includes blood tests for cholesterol and other circulating lipids, for which doctors may ask patients to go without food for 12 hours beforehand.

By collating data from 68 long-term surveys in 21 countries, Professor John Danesh and his collaborators have shown that blood tests on non-fasted patients predict heart and circulatory disease risk just as well as tests on fasted patients.

”For decades, people have been asked to fast overnight before their cholesterol tests,” Professor Danesh said. “These findings indicate that cholesterol measurements are at least as good – and probably somewhat better – when made without fasting.”

Professor Peter Weissberg, Medical Director of the BHF, emphasised that doctors may still require patients to fast for other tests.

“Some people may find that even if your cholesterol test can be done at any time, your GP may ask you to fast before your appointment so that he or she can test accurately for diabetes. If you’re having an overall health ‘MOT’, this will not be uncommon practice.”

The study also sought to resolve controversy among experts over which blood tests best assess a person’s risk of heart attacks and strokes. Some experts have advocated that tests for blood proteins called apolipoproteins should replace the more common tests for cholesterol. As well as these tests, some doctors may also measure blood concentrations of triglycerides, a type of fat molecule.

The results show that measuring total cholesterol and HDL or ’good‘ cholesterol is just as informative as testing for apolipoproteins AI and B. The study also found that triglyceride measurements do not provide any extra information about heart disease risk on top of the other tests.

The findings, published in the Journal of the American Medical Association (JAMA), should influence new cardiovascular guidelines that are being drawn up for doctors in the UK, US and Europe.

“Given the financial pressure the NHS is under, it’s good news that doctors don’t need to spend money on setting up more sophisticated tests based on apolipoproteins," Professor Weissberg added. "But the study underlines the importance of all GPs being able to measure HDL cholesterol as well as total cholesterol, in order to make the best predictions about heart disease risk.”